The present invention pertains to a mirror construction for automotive interior applications such as vanity mirror visors and particularly to a shatter resistant construction for such mirrors.
For several years, visors have included vanity mirrors for the personal grooming of passengers. Some vanity mirrors include illumination means for use under low ambient light conditions such as disclosed in U.S. Pat. No. 4,000,404. In many instances, the vanity mirrors include a cover which covers the vanity mirror when not in use such that the driver is not distracted by reflections from the mirror. Also, when covered, the mirror poses no safety hazard in the event of an accident.
Vehicle mirrors such as visor vanity mirrors, rearview mirrors and the like must meet minimum safety standards for vehicles in the United States and in the European Economic Community (EEC). One standard for the EEC includes that glass shards from a broken mirror must remain on a mirror backing and there be no greater than a 0.010 inch step between adjacent glass shards in the event a mirror is broken during impact. Presently, existing mirror backing materials for glass mirrors do not meet these standards. European vehicles frequently use metal mirrors which are very costly and provide relatively poor images in order to meet such standards. Plastic mirrors also can meet the standards but they are too costly, provide a relatively poor image and are subject to warping under temperature extremes. Some glass mirrors have been covered with a mylar protective film which, however, is very costly and presents a surface subject to scratching with use. Efforts have been made to provide a polypropylene visor core which supports the mirror sufficiently to eliminate breaking. However, adding significant additional weight and material cost to a visor is a commercially unattractive option.
Backing materials which have been used in an effort to meet United States impact standards have included paper with an adhesive layer, mylar tape, masking tape, polyethylene foam adhered to the mirror back and finally latex film which has been adhered to the mirror back. One visor patent suggests a combination of a polyurethene foam material and a backing plate (U.S. Pat. No. 3,926,470). Although these existing backing materials for glass mirrors retain mirror shards on the backing material, they have not proven effective in meeting newer safety requirements nor have they been resistant in preventing shattering of the mirror in the first instance.